The present invention relates to apparatus and methods for forming coils that are used for the winding of a stator of a dynamo-electric machine and for inserting those coils into slots of a stator.
A typical known stator of an electric motor is shown in FIG. 1. The stator includes an annular body 1 having a laminated structure with an inner cylindrical surface 2 and a plurality of longitudinal slots 3. Longitudinal slots 3 receive portions of copper wire coils 4, which constitute the winding W of the stator. Coils 4 are formed in a coiling machine that delivers the formed coils to a coil-inserting tool, such as, for example, the type disclosed in U.S. Pat. No. 3,324,536. Such a coil-inserting tool inserts the coils positioned thereon into slots of a stator, which are aligned over the coil-inserting tool.
Apparatus of the above type is also known that includes first and second coiling stations, an inserting station, and means (typically a platform rotatable around a vertical axis) to bring a coil-inserting tool sequentially to the first coiling station, then to the second coiling station, and lastly to the inserting station. This apparatus is used, for example, to provide stators of the type shown in FIG. 1. Such stators include a primary winding of two coils 4 arranged as shown in FIG. 1, and a secondary winding of two additional coils arranged at 90 degrees with respect to the primary winding coils. The coil-inserting tool receives the first pair of coils for the primary winding at the first coiling station, and the second pair of coils for the secondary winding at the second coiling station. From the second coiling station, the coil-inserting tool is brought to the inserting station where the primary and secondary windings are simultaneously inserted into the stator slots.
For conventional stators of the type shown in FIG. 1, the advantage of two coiling stations is limited, because a single coiling station can form coils for both the primary and secondary stator windings. Moreover, even if the two coiling stations operated in parallel, production capacity is limited because the cycle time of forming coils at a coiling station is often longer than the cycle time of inserting the coils at an inserting station. For example, insertion may be approximately 15 seconds, while forming coils may be approximately 30 seconds. Thus, production capacity is limited by the coiling time.
In view of the foregoing, it would be desirable to provide apparatus and methods with improved production capacity for forming and inserting coils that constitute the winding of a stator of a dynamo-electric machine.